1. Field of the Invention
This invention relates generally to the field of measuring carbon in a sample composition. More particularly, this invention relates to measuring carbon as Total Organic Carbon (TOC), Total Inorganic Carbon (TIC) or Total Carbon (TC) using electrochemical oxidation.
2. Background of the Invention
The need to measure carbon in aqueous samples exists in matrixes from ultra-pure water to waste water and industrial solutions for a variety of reasons. Historically, the analysis equipment to accurately measure carbon in an aqueous solution involved large equipment and hazardous reagents, such as strong acid and oxidizing agents. The use of electrochemical oxidation of carbon may eliminate at least one of these reagents and, when combined with a detection technique to quantify the resultant carbon dioxide gas (e.g., in solution, measured in a headspace or purged from the sample and transported with carrier gas to a detector), promises a versatile, easy to use, and cost-effective alternative for accurately determining TOC levels in a solution. Thus, the development of a safe and cost-effective electrochemical device capable of oxidizing organic carbon and allowing determination of TOC in a sample composition would represent a significant advance in the art.
Electrodes are used in the typical electrochemical cell for oxidation of carbon. The most common working electrode material has typically been carbon-based or made from metals such as platinum, silver, gold, mercury, or nickel. Drawbacks to such electrodes include poor oxidation. Further drawbacks include the self-consuming nature (e.g., reduction/oxidation) of the electrodes themselves. To overcome these limitations, conductive diamond film electrodes have been developed. Diamond film electrodes include a substrate material coated with diamond or diamond-like film wherein the diamond coated electrodes are doped to provide conductivity (e.g., boron doped). Drawbacks to the conventional diamond or diamond-like film electrodes include the tendency of electrodes to fail due to contamination and corrosion. Additional drawbacks include insufficient oxidation, Consequently, there still remains a need for a method and apparatus for measuring carbon using electrochemical oxidation with reduced electrode contamination and corrosion.